Display device

ABSTRACT

An inspection circuit is properly protected in a display device, which the driver IC is not on the terminal area. A liquid crystal display device comprising a TFT substrate having a display area, in which video signal lines are formed, and a terminal area; a counter substrate overlapping with the display area of the TFT substrate; the counter substrate and the TFT substrate are adhered by the seal material, the display area is formed in an area surrounded by the seal material; wherein the flexible wiring circuit substrate connects to the terminal area, the driver IC, which supplies video signals to the video signal lines, is not installed in the terminal area, the inspection circuit is formed between the display area and the terminal area, wherein the inspection circuit overlaps with the counter substrate in a plan view.

CROSS-REFERENCE TO RELATED APPLICATIONS

The application is a continuation of and claims the benefit of priorityunder 35 U.S.C. § 120 from U.S. application Ser. No. 16/735,775 filedJan. 7, 2020, which is a continuation of U.S. application Ser. No.16/104,152 filed Aug. 17, 2018 (now U.S. Pat. No. 10,586,479 issued Mar.10, 2020), and claims the benefit of priority under 35 U.S.C. § 119 fromJapanese Patent Application No. 2017-159963 filed Aug. 23, 2017, thecontents of each of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION (1) Field of the Invention

The present invention relates to a display device, specifically to aplacement of the inspection circuit and a method of inspection when thedriver IC is removed from the terminal area to narrow the frame area ofthe display device.

(2) Description of the Related Art

A liquid crystal display device has a TFT substrate, a counter substrateopposing to the TFT substrate, and a liquid crystal layer sandwichedbetween the TFT substrate and the counter substrate. The TFT substratehas plural pixels; each of the pixels has a pixel electrode and a thinfilm transistor (TFT). Each of the pixels is in an area surrounded bythe scanning lines and video signal lines. A transmittance of light ineach pixel is controlled by liquid crystal molecules; thus, images areformed.

The organic EL display device has a structure that the TFT substrate iscovered by the protecting film, wherein the pixels having the lightemitting elements and TFTs are formed in a matrix form on the TFTsubstrate. Both the liquid crystal display device and the organic ELdisplay device are thin and light weight display devices, thus, they areutilized in various fields.

In such displays, there is a demand that the display area is enlargedwhile the outer size of the display device is kept in the same size.Those displays are called narrow frame displays. In such displays,however, the wiring density of in the frame area becomes high. Thepatent document 1 (Japanese patent laid open 2007-140378) discloses theplacement of the inspection circuits and the inspection terminals insuch narrow frame display devices.

SUMMARY OF THE INVENTION

There is a strong demand to enlarge the display area while the outersize is not enlarged in e.g. the liquid crystal display devices. Theterminal area is necessary to supply powers and signals to the liquidcrystal display device; however, the width of the terminal area alsomust be narrowed in the narrow frame display device. Generally, thedriver IC, which forms the video signals according to signals suppliedfrom outside, is placed on the terminal area, and the flexible wiringcircuit substrate is connected to the terminal to supply powers andsignals.

If the terminal area is further narrowed, the driver IC is removed fromthe terminal area and is set on the flexible wiring circuit substrate.On the other hand, the liquid crystal display device must be inspectedto check whether the wirings have any defects like shorts ordisconnections before the display device is completed.

When the driver IC is removed from the terminal area, the disposition ofthe inspection circuit becomes a problem. The purpose of the presentinvention is to solve the problem of the disposition of the inspectioncircuit when the driver IC is disposed on the flexible wiring circuitsubstrate and the flexible wiring circuit substrate is directlyconnected with the display area.

The present invention overcomes the above explained problem; theconcrete structures are as follows.

(1) A liquid crystal display device comprising: a TFT substrate having adisplay area, in which video signal lines are formed, and a terminalarea, a counter substrate overlapping with the display area of the TFTsubstrate;

wherein a plurality of first terminals to connect with the flexiblewiring circuit substrate and a plurality of second terminals, which areused in an inspection process are formed in the terminal area,

an inspection circuit is formed between the display area and theterminal area in a plan view in the TFT substrate,

the inspection circuit has a plurality of switching portions to connectthe video signal line to either one of the first terminal or the secondterminal,

an insulating film is formed on the inspection circuit at the surfaceopposing to the counter substrate.

(2) An organic EL display device comprising: a TFT substrate having adisplay area, in which video signal lines are formed, and a terminalarea;

wherein an anode is formed on a first organic insulating film, anorganic EL layer is formed on the anode, a cathode is formed on theorganic EL layer, an inorganic insulating film is formed on the cathode,and a polarizing plate is set on the inorganic insulating film,

a plurality of first terminals to connect with a flexible wiring circuitsubstrate and a plurality of second terminals utilized in an inspectionprocess are formed in the terminal area,

an inspection circuit is formed between the display area and theterminal area in a plan view in the TFT substrate,

the inspection circuit has a plurality of switching portions to connectthe video signal line to either one of the first terminal or the secondterminal,

the first organic insulating film is formed on the inspection circuit atthe surface opposing to the polarizing plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the liquid crystal display device, which thepresent invention is applied;

FIG. 2 is a plan view of the conventional liquid crystal display device;

FIG. 3 is a cross sectional view of the display area of the liquidcrystal display device;

FIG. 4 is a plan view of the terminal area and its vicinity of theliquid crystal display device;

FIG. 5 is a cross sectional view of FIG. 4 along the E-E line;

FIG. 6 is an example of the equivalent circuit of FIG. 4;

FIG. 7 is a cross sectional view of FIG. 6 along the A-A line;

FIG. 8 is a cross sectional view of FIG. 6 along the B-B line;

FIG. 9 is a cross sectional view of FIG. 6 along the C-C line;

FIG. 10 is a plan view of an example of wirings in the tilted wiringregion;

FIG. 11 is an example of the inspection circuit;

FIG. 12 is another example of the inspection circuit;

FIG. 13 is polarities of wirings when the inspection is conductedaccording to the inspection circuit of FIG. 12;

FIG. 14 is an enlarged plan view of the terminal area;

FIG. 15 is an enlarged plan view of the terminal area and its vicinityaccording to an embodiment 2;

FIG. 16 is a cross sectional view of FIG. 15 along the F-F line;

FIG. 17 is a plan view of the organic EL display device according to thepresent invention;

FIG. 18 is a cross sectional view of the display area of the organic ELdisplay device;

FIG. 19 is a cross sectional view of FIG. 17 along the G-G line;

FIG. 20 is another example of the inspection circuit;

FIG. 21 is an example of the inspection circuit according to theembodiment 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in detail referring to thefollowing embodiments. The explanation below is made mainly for theliquid crystal display device; however, the present invention isapplicable to other displays like e.g. the organic EL display device.

Embodiment 1

FIG. 1 is a plan view of the liquid crystal display device, which thepresent invention is applied. In FIG. 1, the TFT substrate 100 and thecounter substrate 200 are adhered at their peripheries by the sealmaterial 150; the liquid crystal is sealed inside. In the display area20, scanning lines 11 extend in the lateral direction (x direction) andare arranged in the longitudinal direction (y direction); the videosignal lines 12 extend in the longitudinal direction and are arranged inthe lateral direction. The pixel 13 is formed in the area surrounded bythe scanning lines 11 and the video signal lines 12.

In FIG. 1, the TFT substrate 100 is formed bigger than the countersubstrate 200; the area that the TFT substrate 100 does not overlap withthe counter substrate 200 is the terminal area 30. The flexible wiringcircuit substrate 500 connects with the terminal area 30. Powers,scanning signals, video signals, clock signals are supplied to theliquid crystal display device through the flexible wiring circuitsubstrate 500. The display area 20 and the flexible wiring circuitsubstrate 500 are connected through the terminal wirings 81.

The feature of FIG. 1 is that the driver IC is not installed in theterminal area 30, but only the flexible wiring circuit substrate 500 isconnected to the terminal area 30. Therefore, the area of the terminalarea can be diminished; consequently, the width of the frame can benarrowed. The driver IC is installed in the flexible wiring circuitsubstrate 500.

FIG. 2 is an example of a plan view of the conventional liquid crystaldisplay device. In FIG. 2, the display area 20 is the same as FIG. 1. InFIG. 2, however, the driver IC 510 is installed in the terminal area 30and the flexible wiring circuit substrate 500 is connected to theterminal area 30. Therefore, the terminal area 30 in FIG. 2 is biggerthan that of FIG. 1; consequently, it has a problem for a narrow framearea.

The terminal area in the liquid crystal display device of FIG. 1, whichthe present invention is applied, can be diminished; however, thedisposition of the inspection circuit becomes a problem. In theconventional structure, the inspection circuit is disposed at the areawhere the driver IC is connected in the terminal area. Namely, in theconventional structure, the inspection circuit is covered and physicallyprotected by the driver IC 510 because the inspection circuit isdisposed under the IC chip. The present invention enables to realize ahighly reliable disposition of the inspection circuit and a method ofthe inspection in the structure of FIG. 1 where the flexible wiringcircuit substrate 500 and the display area 20 are directly connectedthrough the wirings 81, namely, the driver IC is not in the terminalarea 30.

FIG. 3 is a cross sectional view of the display area of FIG. 1. Thedisplay area 20 and the terminal area 30 are formed simultaneously inthe TFT substrate, thus, FIG. 3 is for the explanation of the basiclayer structure of the display device. In FIG. 4 and the followingfigures explain the structure of the terminal area and the seal area atthe vicinity of the terminal area; however, TFTs and the wirings in theselecting circuit, the inspection circuit and so on are formed on thesame layers and formed by the same process as for the TFTs or wirings inFIG. 3. FIG. 3 is a cross sectional view of the IPS (In Plane Switching)type liquid crystal display device.

In FIG. 3, the TFT substrate 100 is generally formed by glass; however,when a flexible display is required, the TFT substrate 100 is formed byresin like e.g. polyimide. The undercoat 101, which is a laminated filmof the silicon oxide (SiO) and the silicon nitride (SiN), is formed onthe TFT substrate 100. The role of the undercoat 101 is to prevent thesemiconductor layer 102 from being contaminated by the impurities fromthe TFT substrate 100.

The semiconductor layer 102 is formed on the undercoat 101. Thesemiconductor layer 102 is generally formed by the polycrystallinesilicon (poly-silicon). Since the poly-silicon has a high mobility, theperipheral circuit as e.g. the scanning line driving circuit can beformed simultaneously on the TFT substrate. Other examples for thesemiconductor layer 102 are e.g. the amorphous silicon, the oxidesemiconductor like IGZO (Indium Gallium Zinc Oxide).

The gate insulating film 103 is formed covering the semiconductor layer102. The gate insulating film 103 is the SiO film formed by CVD usingTEOS (Tetraethoxysilane) as the material. The gate electrode 104 isformed on the gate insulating film 103. The gate electrode 104 is madeof e.g. MoW and fowled simultaneously with the scanning lines 11.Further, parts of the terminal wirings in the terminal area 30 areformed by the same material and by the same process as the gateelectrode 104.

After the gate electrode 104 is patterned, e.g. Phosphor (P) or Boron(B) is doped by the ion implantation to give conductivity to thesemiconductor layer 102 other than the area under the gate electrode104. The area directly under the gate electrode 104 becomes the channel102; other areas become the drain region 1021 or source region 1022.

After that, the interlayer insulating film 105 is formed. The interlayerinsulating film 105 is formed by either one of the SiO film or the SiNfilm or the lamination film of the SiO film and the SiN film. Thethrough hole 120 is formed in the interlayer insulating film 105 and thegate insulating film 103 to connect the drain electrode 106 and thedrain region 1021; the through hole 121 is formed to connect the sourceelectrode 107 and the source region 1022. The drain electrode 106 andthe source electrode 107 are formed simultaneously. The video signallines 12 are formed simultaneously with the drain electrodes 106 and thesource electrodes 107. Further, parts of the terminal wirings in theterminal area are formed simultaneously with the drain electrode 106 andetc. The drain electrode 106 or source electrode 107 are formed by e.g.Aluminum (Al) or its alloy sandwiched by Titan (Ti) or by e.g. MoW.

The organic passivation film 108 is formed by transparent resin, likeacrylic, over the drain electrode 106 and the source electrode 107.Since the organic passivation film 108 has also a role of the flatteningfilm, it is formed as thick as 2 μm to 4 μm. The through hole 130 isformed in the organic passivation film 108 to connect the sourceelectrode 107 and the pixel electrode 111, which is formed later.

The common electrode 109 is formed on the organic passivation film 108by the transparent oxide conductor as e.g. ITO. The common electrode 109is formed in common among the pixels. The capacitance insulating film110 is formed by SiN over the common electrode 109. The pixel electrode111 is formed on the capacitance insulating film 110 by the transparentoxide conductor as e.g. ITO. The ITO constituting the common electrode109 and the ITO constituting the pixel electrode 111 also constituteparts of the terminal wirings or terminals in the terminal area 30. TheITO that constitutes the common electrode 109 may be called the firstITO and the ITO that constitutes the pixel electrode 111 may be calledthe second ITO.

The alignment film 112 is formed on the pixel electrode 111 for theinitial alignment of the liquid crystal molecules 301. The pixelelectrode 111 is formed like stripe shaped or comb shaped; when a signalvoltage is applied to the pixel electrode, the line of force as depictedin FIG. 3 is generated between the pixel electrode 111 and the planeshaped common electrode 109; consequently the liquid crystal molecules301 are rotated by the field, thus, the amount of light that passes theliquid crystal layer 300 is controlled.

In FIG. 3, the counter substrate 200 is set over the TFT substrate 100sandwiching the liquid crystal layer 300. The counter substrate 200 isgenerally formed by glass; however, when a flexible display is required,the counter substrate 200 is formed by resin, like e.g. polyimide. Thecolor filter 201 and the black matrix 202 are formed on inner side ofthe counter substrate 200; the overcoat 203 is formed covering them. Thecolumnar spacers 210 are formed on the overcoat 203, which control thespace between the TFT substrate 100 and the counter substrate 200. Thealignment film 204 is formed on the overcoat 203.

FIG. 3 is a layer structure of the display area of the liquid crystaldisplay device; however, the TFTs in the selecting circuit andinspection circuit, etc. formed in the terminal area 30 and in the framearea have the same structure as explained in FIG. 3. Further, wirings inthe selecting circuit and inspection circuit, etc. formed in theterminal area 30 and in the frame area are formed simultaneously withthe gate electrode 104, the drain electrode 106, the source electrode107, the first ITO 109 and the second ITO 111 in FIG. 3.

FIG. 4 is an enlarged plan view of the terminal area 30 and itsvicinity. In FIG. 4, the TFT substrate 100 and the counter substrate 200adhere to each other by the seal material 150; the display area 20 issurrounded by the seal material 150. The TFT substrate 100 that does notoverlap with the counter substrate 200 is the terminal area 30; thesignal terminals 31 (which are not shown in FIG. 4) for connecting withthe flexible wiring circuit substrate 500 and the inspection terminals32 for the inspection are formed in the terminal area 30.

The video signal lines 12 extend in the longitudinal direction (ydirection) in the display area 20. The number of the video signal lines12 are so large, thus, the selecting circuit 60 is formed to decreasethe number of wirings at the terminal area 30. The selecting circuit 60is a switching circuit formed by TFTs. For example, when the signals forthe red pixels, green pixels and blue pixels are written separately, thenumber of terminal wirings can be decreased to ⅓.

The wirings from the selecting circuit connect 60 with the inspectioncircuit 40 via the tilted wiring region 50. The inspection circuit 40 isalso a switching circuit that has many TFTs. The inspection circuit 40switches signals supplied from the signal terminal 31 or the inspectionterminal 32 so that they can be transmitted to each of the tilted wiringregion. The inspection process is conducted through the inspectionterminals 32 before the flexible wiring circuit substrate 500 isconnected.

In this embodiment, the counter substrate 200 covers the inspectioncircuit 40 as depicted in FIG. 4. Therefore, the inspection circuit 40,which has many TFTs, is protected by the counter substrate 200 and theseal material 150. The tilted wiring region 50 extend to the terminalarea 30 and connect with the terminals formed in the terminal area 30.The flexible wiring circuit substrate 500 is connected to the terminals.The driver IC is not installed in the terminal area 30 but is installedin the flexible wiring circuit substrate 500 in FIG. 4.

The structure that the driver IC 510 is installed in the terminal area30 of the TFT substrate 100 is called COG (Chip On Glass); the structurethat the driver IC 510 is installed in the flexible wiring circuitsubstrate 500 is called COF (Chip On Film). The video signals that aresupplied to each of the video signal lines 12 are arranged by the driverIC. Namely, video signals, supplied from outside in serial, aretransformed to parallel arrangement by the driver IC, and supplied tothe display area 20 of the liquid crystal display device. Therefore, inthe case of COF, as the case in the present invention, the number ofterminals increases greatly compared with the case of COG. For example,the number of terminals in COG is around 300, while the number of theterminals in COF increases 5 or six times, which makes as many as 1500to 1800.

FIG. 5 is a schematic cross sectional view along E-E line of FIG. 4. InFIG. 5, the TFT substrate 100 and the counter substrate 200 are adheredby the seal material 150; the liquid crystal 300 is sealed inside. Thevideo signal lines 12, the selecting circuit 60, the tilted wiringregion 50, the inspection circuit 40, terminal wiring 81 and signalterminal 31 are formed on the TFT substrate 100.

In FIG. 5, the selecting circuit 60, the tilted wiring region 50, theinspection circuit 40, etc. are covered by the organic passivation film108, and further, are protected by the seal material 150 and the countersubstrate 200. The terminal wirings 81 extend from the inspectioncircuit 40 to the signal terminals 31. The signal terminals 31 areconnected to the flexible wiring substrate 500 through the ACF(Anisotropic Conductive Film) 501. In the meantime, the terminal wirings81 may be exposed or covered by the capacitance insulating film 110 madeof SiN or the organic passivation film 108, which are depicted in FIG.3.

The feature of FIG. 5 is that the inspection circuit 40, which has a lotof TFTs, is protected by the organic passivation film 108, the sealmaterial 150 or the counter substrate 200, etc. Therefore, thereliability of the inspection circuit 40 is maintained.

FIG. 6 is the equivalent circuit corresponding to FIG. 4. The circuit inFIG. 6 is simplified for easy understanding. In FIG. 6, the video signallines 12 extend in the longitudinal direction (y direction) toward thedisplay area 20 from the selecting circuit 60. The selecting circuit 60has many switches formed by TFTs. The selecting circuit 60 enables towrite the data three times in one frame period; thus, the number of thewirings from the selecting circuit 60 to the terminal area 30 can bedecreased to ⅓.

The tilted wiring region 50 is formed to connect the selecting circuit60 and the inspection circuit 40. The pitch of the wirings in the signalterminals 31 is smaller compared with the pitch of the wirings in theselecting circuit 60; thus, the tilted wirings 51 are formed between theselecting circuit 60 and the inspection circuit 40. Since the pitch ofthe wirings in the tilted wirings 51 is smaller than the pitch of thewirings that extend in the longitudinal direction (y direction), it isdifficult to maintain the space between the wirings in the tilted wiringregion 50. Therefore, the tilted wirings 51 have multi-layer wiringsstructure.

Namely, in the tilted wiring region 50, the every other tilted wiring 51has through holes 90 and 91 to change the layer from e.g.

the drain layer to the gate layer. FIG. 7 is cross sectional view alongthe line A-A in the tilted wiring region 50 of FIG. 6. The wiring 71,51, which is formed on the same layer as the drain electrode 106 (videosignal line 12), extends from the selecting circuit 60 and changes itslayer to the same layer as the gate electrode 104 (scanning line 11) viathrough hole 91 to become the wiring 70, 51; and when the tilted wiringregion 50 ends, the wiring 70, 51 changes its layer to the wiring 71,51, which is on the same layer as the video signal line 12 via thethrough hole 90.

FIG. 8 is a cross sectional view along the B-B line of FIG. 6. Thewiring 71, 51, in FIG. 8, continuously stays on the same layer as thevideo signal line 12 is formed. Therefore, the adjacent wirings can beoverlapped in a plan view; thus, the area for the tilted wiring region50 can be decreased. FIG. 9 is the cross sectional view along the lineC-C of FIG. 6. In FIG. 9, the space between the wirings is smaller thanthe width of the wiring. In the meantime, since the overlapping areaincreases, a danger of the short between the adjacent wirings increases.

Back to FIG. 6, the wirings in the tilted wiring region 50 may cross toeach other in order to decrease the capacitance between the wirings;however FIG. 6 does not have the cross of the wirings to avoidcomplication of the figure. The inspection circuit 40 is located at theplace the wirings again extend in the longitudinal direction (ydirection) after the tilted wiring region 50.

The inspection circuit 40 depicted in FIG. 6 has many switches; thoseswitches are formed by TFTs, consequently include many semiconductorlayers 102. The inspection circuit 40 is protected by the organicpassivation film 108, seal material 150, the counter substrate 200, andetc. as depicted in FIG. 5; thus, reliability of the inspection circuit40 against the outer environment is maintained.

The role of the inspection circuit 40 is to inspect the disconnection inmany wirings or the short among the many wirings. In the tilted wiringregion 50, the tilted wirings 51 extending from the switches 61 in theselecting circuit 60 are formed. In the inspection circuit 40, theinspection switch 41 is formed for each of the tilted wirings 51. Therole of the inspection switches 41 is to switch the connection of thetilted wiring to either one of the terminal wiring 81 or the inspectionsignal wiring 45. The terminal wirings 81 connect with the signalterminals 31, which the flexible wiring circuit substrate 500 isconnected; the inspection signal wirings 45 connect with the inspectionterminals 32, which are used for the inspection before the flexiblewiring circuit substrate 500 is connected.

As depicted in FIG. 4, the inspection terminals 32 are disposed at theboth sides of the group of signal terminals 31. The inspection signalwirings 45, which connect with the inspection terminals 32, extend in xdirection and are arranged in y direction in the inspection circuit 40.The tilted wiring 51 connects with one of the inspection signal wirings45 via inspection switches 41. When the inspection is conducted, theinput to the inspection terminals 32 is subsequently switched;consequently, the disconnection and etc. are inspected in the tiltedwirings 51 and the video signal lines 12, which are beyond the tiltedwirings 51.

According to the structure of FIG. 6, the disconnection or the short inthe wirings from the inspection circuit 40 to the display area 20 can beinspected. Larger area can be inspected by setting the inspectioncircuit 40 at very near the edge of the counter substrate 200.

The liquid crystal display device is generally AC driven. While thereare the frame inversion system, the column inversion system and the dotinversion system in the AC driving method, currently, the columninversion system is adopted most. The column inversion system is thatthe polarities in the adjacent video signal lines are reversed.

In the tilted wiring region 50, the wirings 51 depicted in FIGS. 4 and 6are multi layered to decrease the area for the wirings, namely, thewirings 51 are overlapped in a plan view. In this case, if thepolarities between the adjacent wirings 51 are reversed, a period forwriting the data becomes long due to the bigger capacitance between thewirings.

To prevent this phenomenon, there is a technology as e.g. three wiringsof the same polarity are bound together and a space is set between thesets of three wirings of different polarity. In FIG. 10, negative signalvoltage is applied to the left set of three wirings, positive signalvoltage is applied to the center set of three wirings and negativesignal voltage is applied to the right set of three wirings. The reasonis that: if polarity is the same in the set of three wirings, theproblem of capacitance between the wirings is mitigated.

In this embodiment, as depicted in FIG. 11, a two wiring method isadopted. The two wiring method is that a pair of the inspection wirings45 is constituted by two wirings, which voltages of different polarityare applied. In the tilted wiring region 50 in FIG. 11, negative voltageis applied to the left set of three wirings while positive voltage isapplied to the right set of three wirings. In this structure, however,the short between the three wirings in the set cannot be tested. Torealize more proper inspection, exchanges are made among the tiltedwirings 51 connected to the switch 61 or the switch 41 in the selectingcircuit 60 and the inspection circuit 40.

Only one pair of the inspection wirings 45 is shown in FIG. 11; however,six inspection terminals 32 are formed in the present embodiment, asshown in FIG. 4. Therefore, actually six inspection wirings 45 areformed in the inspection circuit 40 as depicted in FIG. 12. When thepolarity is changed in every other adjacent wiring 45, the inspection ofthe disconnection or the short between adjacent wirings becomes possibleeven in a set of three wirings in the tilted wiring region 50 asdepicted in FIG. 13.

In the meantime, the polarities in the set of three wirings in FIG. 13are only for the period for the inspection; in the time of display,however, the polarities are set as shown FIG. 10. Therefore, both ofhigh speed data writing in the time of display and inspection of all thewirings in the inspection process are possible by adopting sixpolarities method in the inspection circuit 40.

FIG. 14 is a plan view of modified configuration of the terminals 31, 32in the terminal area 30 according to the present invention. Theinspection terminals 32 and the signal terminals 31 for the videosignals are set in the terminal area 30 in FIG. 14. The inspection ofwirings is conducted before the flexible wiring circuit substrate 500 isconnected; the inspection is made by contacting the probes of the testerto the inspection terminals, thus, the size of the inspection terminals32 is bigger than the size of the signal terminals 31 for the videosignals. In FIG. 14, the position of the flexible wiring circuitsubstrate 500 is depicted by the broken line. In FIG. 14, 321 is thearea where the inspection terminals 32 are located and 312 is the areawhere the signal terminals 31 are located.

As depicted in FIG. 14, the terminal area 30 can be utilized efficientlyby setting the inspection terminal area 321 at the both sides of thevideo signal terminal area 312 and at the central region of the terminalarea 30, in other words, between the video signal terminal areas 312. Inthe inspection terminal area 321 at the central region of the terminalarea, the terminal for the power or the terminal for the commonelectrode can be set because a large current flows in those terminals.

Such a configuration makes a width of the flexible wiring circuit 500larger; however, when the tilting wirings are necessary between theinspection circuit 40 and the terminals 31, 32, tilting angle of thetilting circuit can be decreased, thus, it is possible to avoid thepitch between the tilting wirings to become too narrow.

As described above, according to the present invention, the inspectioncircuit can be set at the area protected by the counter substrate 200and the seal material 150, etc. without decreasing efficiency of theinspection in the display device that the driver IC is not set in theterminal area but set in the flexible wiring circuit substrate 500.Therefore, the liquid crystal display device of high reliability can berealized.

MODIFIED EXAMPLE

FIG. 20 is a modified example of the inspection circuit 40. In theexample of FIG. 6, the wirings 51 between the inspection switches 41 andthe signal terminals 31 cannot be tested because the inspection switches41 are formed in the area inside of the counter substrate 200. On thecontrary, in the inspection circuit 40 in FIG. 20, the connectionbetween the wiring 51 and the inspection switch 41 is set near thesignal terminal 31 beyond the edge of the counter substrate 200. Thus,the entire region of the wirings 51 can be inspected.

Embodiment 2

FIG. 15 is another example of the display device, in which the driver ICis not installed in the terminal area but installed in the flexiblewiring circuit substrate 500. A big difference between FIG. 15 and FIG.4 is that the inspection circuit 40 is set adjacent to the edge of theflexible wiring circuit substrate 500 in FIG. 15. FIG. 21 is an exampleof the inspection circuit 40. The inspection circuit 40 is set in theterminal area 30 where the counter substrate 200 does not overlap inFIGS. 15 and 21. In this embodiment too, the connection between thewiring 51 and the inspection switch 41 is set near the signal terminal31. The inspection area of the inspection circuit 40 covers almost allthe display device. In other words, the inspection of the short and thedisconnection in the wirings can be performed in all the area. In thisembodiment, the inspection switches 41, themselves, are near the signalterminals 31, thus a layout of the wirings is easy.

On the other hand, in the structure of FIG. 15, the inspection circuit40 is located between the counter substrate 200 and the flexible wiringcircuit substrate 500 in a plan view; consequently, the organicpassivation film 108 extends into the terminal area 30 to cover theinspection circuit 40, thus, the inspection circuit 40 can be protected.FIG. 16 is a cross sectional view of FIG. 15 along the line F-F. FIG. 16differs from FIG. 5 of the embodiment 1 in that the inspection circuit40 is located between the counter substrate 200 and the flexible wiringcircuit substrate 500.

As described above, the present embodiment has a merit that the shortand the disconnection of wirings can be inspected in almost all the areaof the display device. In addition, the inspection circuit 40 can beprotected since the organic passivation film 108 covers the inspectioncircuit 40.

Embodiment 3

In the embodiment 1 and the embodiment 2, the present invention wasexplained when it is applied to the liquid crystal display device. Thepresent invention is, however, applicable to the organic EL displaydevice since the organic EL display device, too, has video signal lines12, scanning lines 11, etc. and many switches, which are formed by TFTs.In addition, the organic EL display device also has a demand to move thedriver IC from the terminal area 30 to the flexile wiring circuitsubstrate 500 to reduce the terminal area 30, namely to reduce the framearea.

FIG. 17 is a plan view of the organic EL display device. In FIG. 17, thedisplay area 20 and the terminal area 30 are formed; the driver IC isnot installed in the terminal area 30 but only the flexible wiringcircuit substrate 500 is connected to the terminal area 30. The scanninglines 11 extend in the lateral direction (x direction) and are arrangedin the longitudinal direction (y direction). The video signal lines 12extend in the longitudinal direction and are arranged in the lateraldirection. In addition, the power lines 14 extend from upper part to thelower part of the display area 20. The power lines 14 supply current tothe organic EL layers. The pixel 13 is formed in the area surrounded bythe scanning lines 11 and the video signal lines 12 or in the areasurrounded by the scanning lines 11 and the power lines 14.

The scanning line driving circuits 160 are formed at the both sides ofthe display area 20; the scanning lines 11 extend in the lateraldirection (x direction) from the scanning line driving circuits 160 intothe display area 20. The current supply area 170 is fouled beyond theupper part of the display area 20; the current is supplied to each ofthe power lines 14 from the current supply area 170.

In FIG. 17, the selecting circuit 60 is located beyond the lower part ofthe display area 20; the video signal lines 12 extend in thelongitudinal direction (y direction) from the selecting circuit 60 intothe display area 20. The role of the selecting circuit 60 is the same asexplained in the embodiment 1. The selecting circuit 60 and theinspection circuit 40 are connected through the tilting wiring region50. The multi layered wirings are formed in the tilting wiring region50. The structure of the tilting wiring region 50 is the same asexplained in the embodiment 1.

The inspection circuit 40, like in the liquid crystal display device,detects the short between the wirings and the disconnection in thewirings. The switches in the inspection circuit 40 are formed by TFTs.In FIG. 17, the inspection circuit 40 is protected by the polarizingplate 408, adhesives 407, bank 403, the organic passivation film 108 andetc., which are explained later.

The inspection circuit 40 and the flexible wiring circuit substrate 500are directly connected through the wirings 81. The wirings 81 extend iny direction in FIG. 17; it may become tilting wirings according to therelation between the width of the inspection circuit 40 and the width ofthe flexible wiring circuit substrate 500.

FIG. 18 is a cross sectional view of the display area of the organic ELdisplay device. The TFT in FIG. 18 is a driving transistor; however, theorganic EL display device also uses many switching transistors. Thebasic structure of the switching transistor is the same as the drivingtransistor.

In FIG. 18, the structure is the same as in the case of the liquidcrystal display device of FIG. 3 up to formation of the organicpassivation film 108. In FIG. 18, the reflection electrode 401 made ofe.g. Al and the transparent conductive film made of ITO, which works asan anode 402 are formed on the organic passivation film 108. The anode402 connects with the source electrode 107 via through hole.

In FIG. 18, the bank 403 is formed covering the periphery of the anode402. The bank 403 prevents the organic EL layer 404 from gettingdisconnection by the edge of the anode 402; the bank 403 also has a roleto be a partition with the adjacent pixels. The organic EL layer 404,which includes the light emitting layer, is formed in the through holeof the bank 403; the hole is an area between the bank 403 and the bank402 in FIG. 18. The organic EL layer 404 is formed by plural layers likethe hole injection layer, the hole transportation layer, light emittinglayer, the electron transportation layer and the electron injectionlayer.

The cathode 405 is formed covering the organic EL layer 404. The cathode405 is made of a transparent electrode like e.g. the metal oxideconductive film, and is formed in common on all over the display area.In the meantime, the cathode 405 can be made of metal since the metalbecomes transparent when it becomes a thin layer.

In FIG. 18, the protective layer 406 made of e.g. SiN is fouled over thecathode 405. Since the organic EL layer 404 is weak to e.g. moisture,the protective layer 406 curbs intrusion of e.g. moisture to organic ELlayer 405. The polarizing plate 408 is adhered on the protective layer406 through the adhesive 407. The organic EL display device has thereflection electrode 401, consequently the external light is reflected,which deteriorates the visibility of the screen. The polarizing plate408 suppresses the reflection of the external light.

When FIG. 18 is compared with FIG. 3 of embodiment 1, the structure fromthe TFT substrate 100 to the organic passivation film 108 is the same.As described in the embodiment 1, the structure of the TFT that is usedin the display area is applicable to the structure of the TFT that isused in e.g. the inspection circuit 40.

FIG. 19 is a schematic cross sectional view of FIG. 17 along the lineG-G. In FIG. 19, the organic passivation film 108 is formed over thevideo signal wirings 12, the tilting wirings 51, the inspection circuit40, and etc. The organic film of e.g. acrylic, which constitutes thebank 403 s formed on the organic passivation film 108; the protectivelayer 406 made of e.g. SiN is formed on the bank 403. The polarizingplate 408 is adhered to the protective layer 406 through the adhesive407.

In other words, even the elements over the inspection circuit 40 aredifferent, basic structure of FIG. 19 is almost the same as thestructure of the liquid crystal display device shown in FIG. 5 of theembodiment 1. Therefore, the contents explained in FIG. 4 through FIG. 9are applicable to the organic EL display device. On the contrary, theorganic EL display device is not driven by AC but driven by DC.Therefore, the means like combining the wirings of the same polarity inthe tilting wiring region 50 to decrease the capacitance as described inFIG. 10 is not necessary.

In the meantime, the uppermost layer is the polarizing plate in FIGS. 17and 19; however, there is a case that protecting plate made of glass orresin is set on or under the polarizing plate 408. In that case, theinspection circuit can be protected by the protecting plate instead ofthe polarizing plate 408.

What is claimed is:
 1. A display device comprising: a thin filmtransistor substrate (TFT substrate) having a video signal lines formedin a display area, a first switch circuit having plural first thin filmtransistors (first TFTs) which is connected to the video signal lines, asecond switch circuit having plural second thin film transistors (secondTFTs), and a wiring region outside of the display area; and a countersubstrate overlapping with the TFT substrate, wherein, in a plan view,the counter substrate has an edge extending in a first direction, thefirst switch circuit is located between the edge of the countersubstrate and the display area in a second direction intersecting thefirst direction, the second switch circuit is located between the edgeof the counter substrate and the first switch circuit in the seconddirection, the wiring region has plural tilted wires between the secondswitch circuit and the first switch circuit in the second direction, andthe plural tilted wires tilt diagonally with respect to the firstdirection and the second direction.
 2. The display device of claim 1,wherein the TFT substrate further comprises an organic passivation film,the organic passivation film covers the first switch circuit, the pluraltilted wires, and the second switch circuit, and the second switchcircuit overlaps the counter substrate.
 3. The display device of claim2, wherein the TFT substrate and the counter substrate are adhered by aseal material, and the second switch circuit overlaps the seal material.4. The display device of claim 3, wherein the first switch circuit andthe plural tilted wires overlap the seal material.
 5. The display deviceof claim 2, wherein at least one of the first TFTs is connected to atleast one of the second TFTs via at least one of the plural tiltedwires.
 6. The display device of claim 2, wherein the first switchcircuit is formed in a first TFTs formation region, the second switchcircuit is formed in a second TFTs formation region, the first TFTsformation region has a first length in the first direction, the secondTFTs formation region has a second length in the first direction, andthe first length is longer than the second length.
 7. The display deviceof claim 5, wherein the first switch circuit is a selector circuit ofthe video signal lines, and the second switch circuit an inspectioncircuit.
 8. The display device of claim 3, wherein the TFT substrate hasa first area and a second area, the first area overlaps the countersubstrate, the second area is exposed from the counter substrate, theedge of the counter substrate is a border between the first area and thesecond area.